Phenotypic and functional characterization of lymphocytes in autoimmune thyroiditis and in papillary carcinoma

Background: Infiltrates of lymphocytes are found in both autoimmune thyroid disease and papillary cancer and are responsible for thyroid destruction in autoimmune disease. Their role in neoplastic transformation is not yet clear. Materials and Methods: Phenotypic studies and the capacity to undergo apoptosis were assessed on peripheral and gland infiltrating lymphocytes from patients with autoimmune thyroiditis and papillary carcinoma. Results: Peripheral lymphocytes in these patients belong to the same phenotype as the infiltrating lymphocytes. A mixed immune response Tc2 and Tc1 is present in thyroid glands of patients with papillary tumors and the capacity to undergo apoptosis in peripheral lymphocytes from both groups of patients increases. Conclusion: We suggest that a switch from a Th1 (Tc1) in autoimmune thyroid disease to a Th2 or mixed response in papillary carcinoma patients in peripheral blood may help the early diagnosis of thyroid cancer and could be used in autoimmune thyroid disease patient follow-up.